The present invention provides a process for treating water in a treatment plant and a corresponding treatment plant. In particular, the invention has for its subject-matter the reduction and treatment of the sludge in the biological wastewater treatment.
Water is treated in many different ways. In particular, industrial and domestic wastewater is, as appropriate, processed in several stages. One of these treatment stages, especially in the treatment of wastewater, is often a biological treatment stage. In this case, biodegradable material is treated in water by adding to it microorganisms which convert the biodegradable material. This forms sludge which has to be removed from the corresponding reaction chambers in order to ensure the capacity of the tank and the survival of the microorganisms. To this end, separating chambers—so-called secondary clarifiers—are used. As a result of sedimentation in this secondary space, the sludge which comprises the biodegradable materials and the microorganisms is removed and disposed of. Often, a portion of the sludge from the separating chamber is recycled back into the reaction chamber of the biological wastewater treatment in order to maintain a constant activity or amount of microorganisms here. The separated water from the separating chamber can be sent to further treatment steps or, if appropriate, even to the environment.
In order to reduce this sludge, which gives rise to not inconsiderable costs in its disposal, various approaches are already known. For instance, DE 102 15 413 A1 and US 2006/008,661 A1 disclose processes in which ozone is added in a relatively large amount. A similar process is known from DE 199 20 269 A1.
In addition, it has been found that specific types of biodegradable material, for example particular bacteria, are biodegradable only with difficulty by the microorganisms currently used. This leads to unsatisfactory degradation results and relatively high pollution of biological origin in the wastewater on completion of the treatment.
Proceeding from this, it is an object of the present invention to at least alleviate the disadvantages known from the prior art. More particularly, a process and an apparatus should be specified, with which an improved workup result, especially with regard to bacteria which are otherwise difficult to biodegrade, can be achieved.
These objects are achieved by a process for treating water and a corresponding treatment plant having the features of the independent claims. The particular dependent claims are directed to advantageous developments.